1. Field of the Invention
The present invention relates to an extra-discal intervertebral prosthesis implanted outside the disc of a patient's spine to compensate for defects of the spine.
2. History of the Related Art
Systems are known, comprising a ligament in the form of a ring associated with pedicular screws engaged in at least two adjacent vertebrae whose intervertebral disc presents a pathology. Such systems have the drawback of sometimes breaking under the action of the repeated forces of extension that they support, as they are made of textile. In addition, they cause fibroses, like all textiles implanted in the human body. This type of system imperfectly controls the variation in intervertebral flexion-extension and does not allow a precise approach of the vertebral repositioning and of the control of the residual movement between the two vertebrae.
The present invention aims at overcoming these drawbacks and at enabling an extra-discal intervertebral prosthesis better supported by the spine which does not present a risk of rupture and which precisely controls the residual movement in the direction of vertebral flexion and/or extension. Such control is that of the variation of the distance from one pedicle to the other of two adjacent vertebrae during the movement of flexion and/or extension.